The U.S. military is opening all combat unit jobs to women in a landmark decision that would allow female service members to join America's most elite military forces.

"There will be no exceptions. This means that, as long as they qualify and meet the standards, women will now be able to contribute to our mission in ways they could not before," Defense Secretary Ashton Carter announced on Thursday, according to The Washington Post.

With this, women can now join the Navy SEALs, Army Special Forces and other Special Operations Units. Women are already serving in other military units.

This year, two female soldiers became the first women to graduate from the U.S. Army's Ranger School.

Carter said top leaders in the Army, Navy, Air Force and U.S. Special Operations Command approved the proposal to open all military jobs to women.

All services are given 30 days to submit plans to Carter on how to implement the new policy. The military is also mandated to notify Congress.

In January 2013, then-Defense Secretary Leon Panetta rescinded a ban on women serving directly in ground combat units.

The report said some 220,000 jobs, or 10 percent, in the military are closed to women.

President Obama said the Defense Department is "taking another historic step forward" by opening up all positions to women.

"As Commander in Chief, I know that this change, like others before it, will again make our military even stronger. Our armed forces will draw on an even wider pool of talent," Obama said.

Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, did not appear with Carter on Thursday. Dunford recommended that certain jobs be kept closed.

"He understands what my decision is, and my decision is my decision, and we will implement it accordingly," Carter said.

"I have had the opportunity to provide my advice on the issue of full integration of women into the Armed Forces," Dunford's statement said. "In the wake of the Secretary's decision, my responsibility is to ensure his decision is properly implemented."

Carter said opening all jobs to women is aimed at giving military access to every American.

"I'm confident the Defense Department can implement this successfully, because throughout our history we've consistently proven ourselves to be a learning organisation," he said.

Carter cited the 2011 repeal of the ban on openly gay service members as example of how gender integration can be implemented.

Sen. John McCain and Rep. Mac Thornberry, Republican chairmen of the Senate and House armed services committees, respectively, said they will "carefully and thoroughly review all relevant documentation related to today's decision."